This invention relates to cathode ray tube effusive material structures and more particularly to insulative means for supporting a container of effusive material within a cathode ray tube.
In cathode ray tubes of the type conventionally employed in image display applications, at least one effusive material structure, as for example, a getter, is affixed to the forward end of the electron generating means oriented within the neck portion of the tube envelope. An exemplary type of getter structure is one referenced within the art as an antenna getter. This type of structure is usually comprised of a resilient longitudinal positioning member or wand having a curvature therein and a getter container terminally mounted thereon. These antenna-type structures are usually affixed to the terminal portion of the electron gun or generating means in an outward curving manner prior to positioning of the gun assembly within the restrictive neck portion of the tube envelope. The curved resilient positioning member permits flexure thereof to facilitate insertion of the electron gun assembly into the neck portion, while assuring sequential orientation of the forward-extending getter container in a position closely adjacent to the interior surface of the outwardly flared infundibular portion of the tube envelope, outside of the paths of the projected electron beams proximal thereto.
It is conventional practice in the art to coat the interior surface of the funnel portion of the tube envelope, and the forward area of the integral neck portion thereof, with an electrical conductive coating such as Aquadag or graphite. In some tube constructions, bands or areas of resistive coating are also disposed upon the interior surface of the funnel portion in an adjacent or continuous relationship to the conductive coating disposed thereon. Usually associated with the forwardly oriented getter container are skid or sled-like metallic means which facilitate positioning the getter container in spatial relationship with the interior surface of the funnel. Upon inserting the electron gun into the open neck of the tube, the aforementioned sled means of the outwardly-extending getter structure, makes contact with the wall of the neck, and as the insertion-positioning of the electron gun progresses, the forwardly oriented sled means on the getter structure scrapes or slides along the interior surface of the neck portion continuing into the funnel portion of the envelope. While the funnel disposed coatings are conventionally formulated to evidence hard surface characteristics, such pressured contact is sometimes conducive for scraping off particles of the conductive or resistive coatings over which the sled may pass. Such loosened coating materials, being residual within the interior of the tube, become deleterious factors affecting the ultimate quality of the tube. In addition, the aforedescribed antenna getter structure forms a metallic bridge which effects shorting out the electron gun assembly to the internal conductive and/or resistive coatings within the tube. There are occasions, especially when discretely oriented resistive coatings are employed, that a shorting effect to the gun structure is an undesirable condition.